Bill and Melinda Gates, in 2003, listened to village leaders in Momemo, Mozambique, discuss the impact of malaria on their families. The PATH Malaria Vaccine Initiative in Seattle and other groups have received nearly $500 million from the Bill & Melinda Gates Foundation to develop, test, manufacture and distribute a malaria vaccine.

SETH WENIG | Associated Press

Indonesian volunteer health workers travel door to door in their neighborhoods, spraying walls with mosquito repellent in hopes of stopping a major outbreak of malaria in water-soaked areas after the devastating tsunami of December 2004.

The twin announcements of Warren Buffett's $31 billion pledge to the Bill & Melinda Gates Foundation and Bill Gates' decision to leave his day job to run the giant philanthropy himself have awed public health experts. Many are still struggling to comprehend the ultimate impact of these actions for philanthropy and its mission.

To be sure, these historic financial resources have the potential to effect change at a level that only recently was unimaginable. The Gateses have said they hope in the coming decades to see the end of dread diseases plaguing the developing world, such as malaria, tuberculosis and HIV, as well as lesser-known maladies such as leishmaniasis, dengue and hookworm.

It might be tempting for many elected officials to believe that the superbly generous contributions of Gates and Buffett — the two richest men on the planet — eventually will eradicate diseases that have kept poor countries locked in a cycle of poverty.

After all, there is little domestic constituency in rich countries to address these problems, aside from a handful of Hollywood and rock celebrities, and a few visionary philanthropists.

The Gates Foundation, however, cannot go it alone; its efforts, no matter how well funded, will be fruitless unless our political leaders work to build the framework necessary to end the spread of epidemics.

While the Gates Foundation has been hugely successful in supporting existing methods and inspiring new ways to fight neglected diseases, we must not forget that many of the drugs and vaccines that are needed in poor countries already exist, but are not delivered to those who need them because of the lack of political will or social acceptance.

As the appropriate stewards of public health, government leaders — in both the developed and developing world — can focus attention, generate support and create innovative public policy mechanisms that can make a difference in the fight against disease.

While financial resources are critical, money alone will not end an epidemic.

In the three-decade fight against AIDS, we have witnessed great political leadership in Senegal, Uganda and Thailand staving off disaster. We also lived through the political abdication in the United States during the 1980s and again, more recently in South Africa, with dire results.

After last week's announcement, Buffett said he was moved to make this pledge as he realized that "a market system has not worked in terms of poor people." As a shrewd investor, Buffett has placed his resources in the hands of a successful organization with the confidence that government will do its part to ensure that philanthropy can effectively support and supplement the work of scientific institutions, advocates, industry and international NGOs.

The Gates Foundation has successfully used this public-private partnership model to develop new products, build alliances among rival organizations and mend fences between erstwhile antagonists — like the pharmaceutical industry and AIDS activists.

The Gates' commitment of $1.5 billion to the Global Alliance for Vaccines and Immunization has spurred other private and public sector giving; today that alliance is on target to save 10 million poor children from preventable childhood diseases. Yet, it should be noted that the work of the alliance is only possible with the direct and enthusiastic participation of African and Asian government leaders, who see the enormous value of immunization campaigns.

Until recently, experts believed that it was impossible to develop a vaccine to end the spread of malaria, which kills more than 1 million people — most them children under 5 in sub-Saharan Africa.

The PATH Malaria Vaccine Initiative has demonstrated a "proof of concept," which shows that it is indeed possible to prevent malaria infection through a vaccine.

The Malaria Vaccine Initiative also funds research projects at the U.S. Department of Defense, filling a void left by the appropriators who fail to fund programs that could save millions of lives each year. One sustainable and lasting consequence of the Buffett announcement would be for Congress to increase malaria vaccine research at both the Defense Department and the National Institutes of Health.

The Gates Foundation has created a sea change in the global health field. The mammoth scope of that change will emerge as more innovation occurs, more diseases are addressed, more players are involved and more valuable resources are employed than ever before.

But even with Warren Buffett's additional billions, we cannot forget that the success of the foundation and its partners' — indeed, every organization working to fight disease — depends on an equivalent sea change in how our governments lead.

Jim Jones is the former executive vice president of the Vaccine Fund and now leader of the global health practice at APCO Worldwide, a communications and public-affairs company in Washington.